Backpacks for day use are well known, and their use has increased dramatically in recent years. Frameless backpacks rely on shoulder straps, and, optionally, hip straps, to carry the load. These backpacks are used for day hiking and other outdoor recreational activities, as well as by students for carrying books and supplies between school and home. Many students today need to carry more books and supplies than they have in the past due to the emphasis being placed on improving schools and the quality of education afforded young people, resulting in heavy loads being carried in the students' backpacks.
Along with the heavier loads being carried more frequently by these frameless packs comes the increased potential for fatigue, discomfort, poor posture, and even musculoskeletal disorder and injury. This places a premium on backpack design to minimize such potential. However, the suspension systems in many such backpacks are simply incapable of providing an ergonomically correct fit. A backpack with standard shoulder straps primarily carries the load on the shoulders. However, the more a load can ride on the hips, the less load pressure there is on the shoulders. Further, the closer the load is to the back of the user, the more upright the user is able to walk, and, consequently, there is less pressure on the hip joints.
If the load in the backpack is compressed, it has less tendency to shift around when the user is moving, jumping, or bending over. The more a load moves, the more the body has to work and move to compensate for the load shifting. The more the body has to move and work to compensate, the greater the chance for injury or body stress. Thus it would be desirable to provide a backpack that moves the load closer to the back and in the direction of the lower back and hips, and also helps to stabilize the load in the backpack.
U.S. Pat. No. 6,164,509 to Gausling et al. discloses a backpack with a shoulder strap secured at one end to a top edge of a body side panel of the backpack. The strap extends across a lower portion of a lateral side of the backpack, and is secured to the backpack at a junction between the lateral side and an outer side of the backpack. Another strap is connected at its first end to the shoulder strap, extends beneath the backpack body, and is connected at its other end to a junction between the bottom of the backpack body and the outer side of the backpack body. The weight of the contents of the backpack act to compress the outer side of the backpack body toward the body when the back is placed on a user's shoulders, thereby shifting the weight closer to the user's back. Gausling is limiting in that it has a complicated construction requiring excessive straps, and, therefore, one that has increased manufacturing costs and potential for functional and maintenance problems.
It is an object of the present invention to provide an improved backpack that reduces or overcomes some or all of the difficulties inherent in prior known devices. Particular objects and advantages of the invention will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of certain preferred embodiments.